The invention relates to a bearing bushing assembly for a telescopic steering shaft, comprising an outer tube and an inner tube, according to the preamble of claim 1 and to a steering system equipped therewith for a motor vehicle according to the preamble of the additional independent claim. The invention further relates to a module composed of the steering shaft and bearing bushing assembly and to the use thereof for a steering system. The invention relates in particular to a bearing bushing assembly and to a steering system equipped therewith, in which the bearing bushing assembly comprises a bearing bushing, which is seated against the inner tube and made of an inflexible plastic material, and a sealing element, which is molded onto the bearing bushing and made of an elastic plastic material, for connecting the inner tube to the outer tube in an axially movable and sealing manner.
Telescopic multi-piece steering shafts or telescopic steering shafts generally are provided with a bearing bushing assembly, comprising a bearing bushing and a sealing element that is designed as a sealing ring or wiper seal and used to guide the inner tube in the outer tube while sealing the two tubes with respect to each other. DE 10 2006 012 057 A1 proposes a bearing bushing assembly that is provided for a telescopic steering shaft, which comprises an outer tube and an inner tube. The bearing bushing assembly described comprises a bearing bushing made of inflexible, hard plastic material, this being polyamide, and a sealing element molded thereon, which is made of a flexible plastic material, this being an elastomer or plastic rubber, whereby an axially movable and sealing connection is created between the inner tube and outer tube. The sealing element, which is designed as a sealing ring or wiper seal, comprises, in particular, a sealing lip, which is seated against the inner tube or inner steering shaft. While the provided sealing ring or wiper seal reportedly offers reliable sealing against moisture and dirt, the use of such a design in steering systems revealed that the conventional bearing bushing assemblies contribute to a significant extent to the transmission of acoustic and mechanical vibrations between the chassis and the driver's cab. However, these disturbances are to be prevented, or at least significantly reduced.
It is therefore the object of the present invention to further improve a bearing bushing assembly of the type mentioned above so that the drawbacks described above are advantageously overcome. In particular, the bearing bushing assembly should have a sealing effect and also a noise-reducing effect.